Vehicle transmissions of the type set forth above are well known to the art as shown, for example, in JP, U No. 52-160770. A speed change transmission performed between input and output shafts is usually accompanied by a speed reduction between the shafts so that torque is higher at the output shaft than at the input shaft. Consequently, a synchronizer clutch mounted on an input shaft of low torque may be of a small capacity as compared to a synchronizer clutch mounted on an output shaft of high torque.
With respect to such a vehicle transmission, an unexpected start of the vehicle has sometimes been experienced at a neutral condition of the synchromesh change mechanism due to some torque transmitted through a synchronizer clutch of a neutral condition. Such a torque transmission may be caused by a drag effect of viscous lubricant oil existing between the input shaft and a change gear which is rotatably mounted on the input shaft and is to be coupled to this shaft by the synchronizer clutch. The torque is transmitted from the change gear to another gear, which is fixedly mounted on the output shaft and is in constant mesh with the former change gear, and then to the output shaft so as to cause a rotation of this shaft.
A simple solution to this problem is that the output shaft is associated with a brake which constantly applies a relatively small braking force to this shaft. Such a brake is known, for example, from JP, U No. 59-166053. However, a brake of this type is operable to brake the shaft even when the vehicle is traveled under an operated condition of the change mechanism. This is not preferred in view of energy loss resulting therefrom and in view of durability of the brake.
Accordingly, a primary object of the present invention is to provide a vehicle transmission in which a synchromesh change mechanism including synchronizer clutches is associated with a brake which is operable to brake the output shaft of the change mechanism only at the neutral condition of this mechanism and which is arranged in a dead space within the change mechanism such that it is easily connectable to a control mechanism for the synchronizer clutches so as to be actuated in the neutral condition of the change mechanism.
An attendant object of the invention is that the brake is provided in a simple and compact fashion.
A further attendant object is to provide a vehicle transmission in which the brake is operated in response to the shifting operation of the change mechanism through operating means which does not restrict the arrangement of another mechanisms.